Leetcode problem 1603 design a parking system implemented in rust

design_parking_system_1603.rs

enum CarType {
    Big(i32),
    Med(i32),
    Small(i32)
}

struct ParkingSystem {
    big: CarType,
    medium: CarType,
    small: CarType
}

impl CarType {
    fn get_count(&self) -> i32 {
        match self {
            CarType::Big(count) => *count,
            CarType::Med(count) => *count,
            CarType::Small(count) => *count
        }
    }

    fn remove_car(&mut self) {
        match self {
            CarType::Big(count) => *count -= 1,
            CarType::Med(count) => *count -= 1,
            CarType::Small(count) => *count -= 1
        }
    }
}


/** 
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl ParkingSystem {

    fn new(big: i32, medium: i32, small: i32) -> Self {
        Self {
            big: CarType::Big(big),
            medium: CarType::Med(medium),
            small: CarType::Small(small)
        }
    }
    
    fn add_car(&mut self, car_type: i32) -> bool {
        match car_type {
            1 => {
                if self.big.get_count() > 0 {
                    self.big.remove_car();
                    return true;
                }
                return false;
            },
            2 => {
                if self.medium.get_count() > 0 {
                    self.medium.remove_car();
                    return true;
                }
                return false;
            },
            3 => {
                if self.small.get_count() > 0 {
                    self.small.remove_car();
                    return true;
                }
                return false;
            },
            _ => {
                return false;
            }
        }
    }
}

/**
 * Your ParkingSystem object will be instantiated and called as such:
 * let obj = ParkingSystem::new(big, medium, small);
 * let ret_1: bool = obj.add_car(carType);
 */